clark



No. 612,705. Patented 06L l8, I898. n. s. CLARKpf GRIPPEB FOR PRINTINGPRESSES, 8w.

(Application filed June 1, 1 s97.

(No mm.)

3 Sheets-Sheet l.

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ATTOPA/EK' "No. 6l2,705. Patented Oct. l8, I898.

u. s. CLARK. GBIPPEB FOR PRINTING PRESSE S, 81.0.

(Applicatiqn-filad June 1, 1597.

(No man 3 sheets sneet 2.

k WITNESSES: lA/l/E/VTOF ATTORNEY.

THE naRms PETERS no. rum-044mm, WASHINGTON, a. c.

Patented Oct. 183391;. o s. CLARK. GRIPPER FDR PRINTING PRESSES, 81.0.

7 (Application filed June 1,1 897. v

(No Model.)

a Sheets-Sheet 3.

ATTORNEY.

m: "cams PETERS ou/wufaumo WA$NINGYON a c NlTE STATES DWIGHT S. CLARK,OF BOSTON, MASSACHUSETTS, ASSIGNOR TO THEFORBES LITIIOGRAPHMANUFACTURING COMPANY, OF SAME PLACE.

GRIPPER FOR PRlNl'lNG-PRES SES, 80C.

SPECIFICATION forming part of Letters Patent No. 612,705, dated October18, 1898.

Application filed Tune 1, 1897. Serial No. 638,995. (No model.) i

To all whom it may concern:

Be it known that I, DWIGHT S. CLARK, a citizen of the United States, anda resident of Boston, in the county of Suffolk and State ofMassachusetts, have invented a new and useful Improvement in Grippersfor Printing- Presses and Like Machines, of which the following is aspecification.

This invention is related to a large number of devices for seizing andtransporting sheets of paper from a feed-board through a printingpress,bronzer, or similar machine to which paper is fed; and it is moreespecially designed to make the seizure and grasp of a sheet morecertain and precise than usual. Apparatus of the sort hitherto employedconsists, in practically all cases, of a number of thin bent fingersfast to a rocking shaft concealed and journaled within a suitable gap inthe periphery of an impression or analogous cylinder. Thesegripper-fingers are so adjusted that the partial revolution of the shaftthat carries them closes their thin ends upon the leading edge of asheet of paper presented to them and carries it with the revolvingcylinder, or, having already held a sheet, they are thrown back into thegap out of the way and the sheet is let go for delivery. As is wellknown in the case of a gripper mechanism of this kind, certainirregularities occur which are partly due to the forward impulse whichthe gripper-fingers give to the sheet of paper at the moment they fallupon it (inasmuch as the impact is by no'means radial) and partly to theunevenness in the paper as it lies at the edge of the gap. These causesof irregular seizure are greatly increased when the spring which closesthe grippers is made quick and powerful in action and when the stock tobe handled is stiff and unyielding in its nature and has to be held downwith a strong pressure. In my invention I counteract such evils byclosing the gripper-fingers, not at a single blow, but by two impulses,the first actuated by a very feeble pressure and the second immediatelyafter it by a relativelyheavy pinch on the paper, which holds itimmovable.

In the diagrammatic drawings which are part of this specification,Figure 1 shows in elevation the end of an impression-cylinder and partof the press-frame with the necessary apparatus attached, the positionbeing such that the closed grippersare just about to receive the secondimpulse. In Fig. 2 a similar elevation on a much larger scale representsthe open gripper just before it first closes on the paper. Fig. 3 is anenlarged view similar to Fig. 1.' Fig. 4 shows the position of thegripper apparatus after the second pinch upon the paper has begun. Fig.5 shows the moment when the releasing of the second pinch takes place,to be followed by the opening of the gripper-fingers immediatelyafterward. Fig. 6 is a plan View of part of the cylinder with thegripper apparatus within and without the gap and part of thepress-frame. Figs. 7 and 8 give details of the adjustable cam and itssupports, which accomplish the second pinch.

In the figures, 10 is the impression-cylinder of a printing-press towhich my gripper mechanism is attached. The gripper-shaft 12 carrieswithin the gap the fingers 14 and outside the tumbler-cam 16 as usuallyconstructed. This cam is actuated and the grip per-shaft oscillated toand fro by the pins or buttons 18 and 20, respectively, and itsposition, as well as the pressure it exerts upon the paper when closed,is further controlled and maintained by the compressed spring 22 in theWell-known way; but this spring is made weak and but slightly compressedand dependence is not put upon it for the efficient holding of thepaper. On the contrary, the gripper-fingers are made of thin elasticmetal and when they strike the edge of the sheet presented to them fromthe feed-board 24 it is with a gentle impact that hinders a rebound asWell as thesudden coercing of unevenness in the paper and its propulsionforward, which in a greater or less degree is common in all presses andknown to be largely influenced by the strength of the blow effected bythe spring 22. After the sheet has been seized in this manner the shaft12 has imparted to it a further fractional rotation in the closingdirection whereby the pressure exerted by the fingers upon the paper isconsiderably increased. This is accomplished by the auxiliary cam 26,which is adjustable tumbling-cam at 32, which in this relation plays thepart of a lever on the shaft, and by moving it on its socket 34, whereit may be held in any desired position by the set-screw 36, the amountof the additional rotation to which the gripper-shaft is subjected, andconsequently the increase of pressure 011 the pa per exerted by thegripper-fingers, is under perfect control provided the swing of the cam36 be made sufficient and can be properly timed. This is allaccomplished by the pins 18 and 38 acting on the curved ends of theoscillating piece 30. This piece is further controlled and locked in itstwo positions by the compressed spring 40 from its attachment at 41forcing said piece against its adjustable stops 42 and 44. When the pin18 has thrown the tumbling-cam 16 over and closed the gripper-fingers onthe paper, it meets immediately afterward at 46 the inclined end of theoscillating piece 30 and throws that piece over, whereby the cam isbrought into action and the second pinch maintained upon the paper tillthe inclined surface at 48 meets the fixed pin 38, the piece thrownback, and the tumbling-cam immediately afterward opened by the pin20,whioh operates the inner end of the tumbling-cam and releases thesheet for delivery.

From the foregoing it will be seen that the sheet of paper is taken bythe grippers, constructed as described, in a very favorable manner, forthe fingers may be made thin and light and under the influence of a weakspring they will fall gently upon the leading edge of the sheet withoutthe momentum and rebound which are common with heavy stiff grippers orthe oblique blow forward given with force enough to move the sheet. Thenthe supplemental angular movement of the gripper shaft, which followsimmediately, though very small in amount, gives a very positive andsustained increase of pressure upon the paper, which is effectedsilently and without jar and may be apportioned in amount to the weightand resistance offered by the stock to be handled.

It is evident that the devices I have described as best adapted for theobjects in view may be changed in many waysas, for instance, a leverindependent of the tumblingcam may be made fast to the shaft andoperated directly by a cam upon the press-frameand I do not thereforeconfine myself to the specific devices I recommend so long as theprinciple upon which my invention is based is maintained, and it will befound that any original gripper movement analogous to that shown anddescribed, of which there are several, with modifications of more orless importance, will admit of combination with my auxiliary cam or itsequivalent, resulting in the supplemental increase of pressure on thepaper determined by its action in the manto lightly clasp a paper sheetby the first or closing movement, and a second mechanism for increasingthe pressure of the gripperfingers on the paper sheet after the same hasbeen seized and held, all combined substantially as described.

2. A gripper mechanism adapted to grasp and hold the edge of a sheet ofpaper fed thereto; in combination with a cam-actuated lever on thegripper-shaft adapted to continue to a definite extent the partialrotation of the shaft after the impact of the gripper-fingers, wherebythe sheet is held with increase of pressure; substantially as described.

3. In a gripper mechanism, agripper-shaft carrying fingers adapted tofall upon and grasp the sheet; in combination with a spring to hold thefingers closed or open; with a cam upon the shaft to throw the fingersover in either direction; and with a second auxiliary cam arranged andtimed to act in like directions after the first has closed and before ithas opened the fingers, and adapted to give a supplemental increase ofpressure thereto when in contact with the sheet; substantially asdescribed.

4. In a gripper mechanism, a gripper-shaft carrying fingers adapted tofall upon and clasp the sheet; in combination with a light spring tohold the fingers closed or open; with a tumbling-cam upon thegripper-shaft to throw the fingers over in either direction; with asupplemental cam within operative range of a lever on the gripper-shaftand adapted to continue the rotation of said shaft through apredetermined angle after the tumbling-cam has closed the fingers; andwith stationary buttons to actuate the cams at proper times whereby theelastic gripper-fingers hold the sheet with a pressure definitelyincreased; substantially as described.

5. In a gripper mechanism, a tumbling-cam in combination with asupplemental cam functionally placed in reference thereto, and adaptedto continue definitely the angular motion thereof after thegripper-fingers have closed; with a spring to lock the supplemen tal camin its extreme positions; and with stationary buttons to throw it in andout of operation at the proper times; substantially as described.

DVVIGIIT S. CLARK.

\Vitnesses I-I. SNYDER, M. E. MILLIKEN.

